# coefficient of friction

## Problem 533 | Friction

**Problem 533**

A uniform bar AB, weighing 424 N, is fastened by a frictionless pin to a block weighing 200 N as shown in Fig. P-533. At the vertical wall, μ = 0.268 while under the block, μ = 0.20. Determine the force P needed to start motion to the right.

## Problem 529 | Friction

**Problem 529**

As shown in Fig. P-529, a homogeneous cylinder 2 m in diameter and weighing 12 kN is acted upon by a vertical force P. Determine the magnitude of P necessary to start the cylinder turning. Assume that μ = 0.30.

## Problem 526 | Friction

**Problem 526**

A ladder 6 m long has a mass of 18 kg and its center of gravity is 2.4 m from the bottom. The ladder is placed against a vertical wall so that it makes an angle of 60° with the ground. How far up the ladder can a 72-kg man climb before the ladder is on the verge of slipping? The angle of friction at all contact surfaces is 15°.

## Problem 525 | Friction

**Problem 525**

A uniform ladder 4.8 m ft long and weighing W lb is placed with one end on the ground and the other against a vertical wall. The angle of friction at all contact surfaces is 20°. Find the minimum value of the angle θ at which the ladder can be inclined with the horizontal before slipping occurs.

## Problem 524 | Friction

**Problem 524**

A horizontal arm having a bushing of 20 mm long is slipped over a 20-mm diameter vertical rod, as shown in Fig. P-524. The coefficient of friction between the bushing and the rod is 0.20. Compute the minimum length L at which a weight W can be placed to prevent the arm from slipping down the rod. Neglect the weight of the arm.

## Problem 523 | Friction

**Problem 523**

A force of 400 lb is applied to the pulley shown in Fig. P-523. The pulley is prevented from rotating by a force P applied to the end of the brake lever. If the coefficient of friction at the brake surface is 0.20, determine the value of P.

## Problem 522 | Friction

**Problem 522**

The blocks shown in Fig. P-522 are separated by a solid strut which is attached to the blocks with frictionless pins. If the coefficient of friction for all surfaces is 0.20, determine the value of horizontal force P to cause motion to impend to the right. Assume that the strut is a uniform rod weighing 300 lb.

## Problem 521 | Friction

**Problem 521**

In Fig. P-519, if μ = 0.30 under both blocks and A weighs 400 lb, find the maximum weight of B that can be started up the incline by applying to A a rightward force P of 500 lb.

## Problem 520 | Friction

**Problem 520**

Referring to Fig. P-519, block A weighs 4 kN and B weighs 3 kN. If μ = 0.20 under B, compute the minimum coefficient of friction under A to prevent motion.

## Problem 519 | Friction

**Problem 519**

In Fig. P-519, two blocks are connected by a solid strut attached to each block with frictionless pins. If the coefficient of friction under each block is 0.25 and B weighs 2700 N, find the minimum weight of A to prevent motion.